Feel Like You’ve Run a Marathon? Long COVID Study Suggests Why - Healthrising

Consul

Senior Member
Messages
318
Likes
1,061
Nice writeup by Cort Johnson on a recent long covid study:

https://www.healthrising.org/blog/2022/09/26/long-covid-blood-vessels-marathon/

An excerpt

The authors didn’t employ people with ME/CFS in the study but highlighted the “broad overlap” between the two diseases and referring to Wirth and Scheibenbogen’s ME/CFS hypothesis proposed that both feature problems with calcium dysregulation that in turn affects the adrenergic and muscarinic receptors that regulate blood flows.
Interresting theory.
 

Pyrrhus

Senior Member
Messages
4,171
Likes
12,772
Location
U.S., Earth
The blog tries to link the research to the currently popular "ischemia-reperfusion hypothesis", which proposes that PEM is caused by improper blood flow:

The study used a technique called “flow-mediated skin fluorescence (FMSF) which the authors stated was “uniquely suitable” for assessing the microcirculation during periods of low blood flow (transient ischemia). A recent hypothesis proposed that people with long COVID or ME/CFS were in a chronic state of transient ischemia due to inadequate blood flows.
Putting aside the fact that "chronic transient ischemia" is an oxymoron, the "ischemia-reperfusion hypothesis" is indeed a popular theory right now due to interest in the cardiovascular manifestations of a coronaviral infection. However, upon further inspection, this theory falls flat.

Specifically, the symptoms of PEM are nothing like the symptoms of ischemia-reperfusion injuries. Whereas PEM symptoms are generalized and varied, ischemia-reperfusion injuries tend to produce localized, well-defined symptoms.

For example, ischemia-reperfusion injuries in limbs can produce myalgia and paresthesias, which is something like Delayed-Onset Muscle Soreness (DOMS) with Peripheral Neuropathy (PN). Inflammation markers in such ischemia-reperfusion injuries would likely be elevated, whereas inflammation markers in PEM are not reliably elevated.

An ischemia-reperfusion injury to the brain would produce stroke-like symptoms, essentially a Transient Ischemic Attack (TIA). Although cognitive exertion can trigger PEM, it is not at all clear how cognitive exertion could produce a TIA.

So really, PEM is nothing like ischemia-reperfusion injuries.